Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 22: Correlated Electrons: Quantum-Critical Phenomena 2
TT 22.8: Vortrag
Mittwoch, 25. März 2009, 11:45–12:00, HSZ 03
Conduction Electron Spin Resonance (CESR) of the itinerant magnets ZrZn2 and NbFe2 — •Tobias Förster1, Jörg Sichelschmidt1, Manuel Brando1, Noriaki Kimura2, Rafik Ballou3, and Frank Steglich1 — 1Max Planck Inst. f. Chem. Physik Fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden,Germany — 2Center f. Low Temp. Scien., Tohoku University, Sendai, Miyagi 980-8578, Japan — 3Inst. Nèel, CNRS, B.P. 166, 38042 Grenoble Cedex 9, France
The two Laves phase compounds ZrZn2 and NbFe2 belong to the rather small group of low temperature itinerant magnets. ZrZn2 has a cubic structure and shows a ferromagnetic (FM) order with a small ordered moment at TC=27.5 K. When applying pressure the FM phase transition becomes first order and disappears around 16.5 kbar[1]. The properties of ZrZn2 are well described by the concept of a marginal Fermi liquid[1]. In the light of these recent findings we reinvestigated the CESR on high quality single crystals of this compound.
NbFe2 has a hexagonal structure and possesses a magnetically ordered ground state (TN=10 K) which is believed to be of spin-density-wave (SDW) type. Signatures of a logarithmic Fermi-liquid breakdown [2] suggest the existence of a quantum critical point on the Nb-rich side of the phase diagram. In our contribution, we will present the first CESR measurements on a slightly Nb-rich single crystal with TN=3.6 K, which shows an intriguing and unusual behavior.
[1] R. Smith et al., Nature 455, 1220 (2008).
[2] M. Brando et al., Phys. Rev. Lett. 101, 026401 (2008).